Light vector dark matter with scalar mediator and muon g−2 anomaly

Abstract

We study a model with a vector dark matter (DM) candidate interacting with the standard model (SM) charged leptons through a scalar portal. The dark matter candidate acquires mass when the complex scalar breaks an Abelian gauge symmetry spontaneously. The scalar interacts with the SM charged leptons through a dimension-6 operator. The scalar mediator induces elastic scattering of dark matter with electrons at tree level and also DM-nucleon interaction when the effects from scalar-Higgs mixing are taken into account. Given the recent results from Xenon1T upper bounds on DM-electron elastic scattering cross sections where the strongest sensitivity lies in the range $\ensuremath{\sim}\mathcal{O}(1)\text{ }\text{ }\mathrm{GeV}$, we find the viable space in the parameter space respecting constraints from the observed relic density, direct detection, muon $({g}_{\ensuremath{\mu}}\ensuremath{-}2)$ anomaly, ${e}^{+}{e}^{\ensuremath{-}}$ colliders, electron beam-dump experiments and astrophysical observables. It is shown that the current upper bounds of Xenon1T on DM-electron interactions are partially sensitive to the regions in the viable parameter space which is already excluded by the electron beam-dump experiment, Orsay. We also find that there are viable DM particles with masses $\ensuremath{\sim}\mathcal{O}(1)\text{ }\text{ }\mathrm{GeV}$ evading the direct detection but standing well above the neutrino floor. Almost the same viable regions are found when we apply the direct detection upper limits on the DM-proton spin-independent cross section.